The invention relates to the field of reproduction technology and is directed to an apparatus for the deflection of an optical beam, which is composed of at least one prism having at least one reflection face which is rotatably seated with respect to a rotational axis.
Light beam deflection devices are employed, for example, in scanner elements of originals scanner devices or in recording elements of recording devices.
In an originals scanner device, also referred to as an input scanner, a light beam generated in a scanner element is conducted over an original to be scanned point-by-point and line-by-line, and the scan light reflected by the original or transmitted through the original is converted into an image signal in an optoelectronic transducer. In a recording device, also referred to as a recorder, exposer or output scanner, the light beam acquired in a recording element is intensity-modulated by an image signal for recording information and is conducted point-by-point and line-by-line over a light-sensitive recording material.
In the case of a flat bed device, the holder for the original or for the recording material is a planar surface over which the light beam is guided point-by-point and line-by-line, and which moves relative to the scanner element or recording element.
In the case of an inside drum device, the holder for the original or for the recording material is designed a stationary half-shell or trough. The scanner element or recording element moves parallel to the longitudinal axis of the half-shell, and the light beam is radially guided over the original or the recording material in the half-shell perpendicularly relative to the longitudinal axis.
A light beam deflection means comprising a prism is disclosed by DE-C-39 18 075. An incident light beam here is first introduced into the prism via a light entry face and is inwardly reflected at an exit face. Another reflection occurs at a further limiting surface and the light beam is refracted when it exits the prism. The prism has an asymmetrical mass distribution with respect to the rotational axis. As a consequence of the centrifugal forces caused by the asymmetrical mass distribution, this light beam deflection means can only be operated in a limited speed range. Over and above this, considerable air turbulence occurs given higher speeds as a consequence of a shaping that is asymmetrical with reference to the rotational axis, this air turbulence resulting in the creation of noise.
Another light beam deflection means that is essentially composed of a prism is disclosed by U.S. Pat. No. 4,878,720. Here, too, the prism has an unbeneficial shaping as well as a mass distribution that leads to considerable, asymmetrical centrifugal forces as well as to a creation of noise.